3D glasses for an SGI

[Mark Hoekstra] is a true SGI enthusiast, and he proves it with these 3D glasses for an SGI. Taking advantage of the SGI’s stereo viewport, [Hoekstra] created a controller for a pair of CrystalEyes glasses that would allow them to be used with the SGI.

[Hoekstra] used the schematic from [M.C.D. Roos]’s similar project, which used old Asus 3D VR glasses. This project can theoretically be done with any LCD-shutter glasses, the only important thing to know is the maximum shutter voltage the glasses will take. [Hoekstra] felt his way through building the board by common sense alone and somehow managed to avoid any shorts. The board only makes three connections to the glasses: an out to the left lens, one to the right, and a ground wire. After building the controller board out of an LM324 chip and a customized segment of perf board, he learned that he needed a monitor capable of displaying a relatively high bit depth at 100Hz, or 50Hz per eye. He tested the glasses with a game called Hacknoid after making a few last minute changes on the board (forgot the ground fuse), and he was soon making himself dizzy with his functioning 3D glasses.

I had no idea such glasses existed – and are so cheap! how hard would it be to connect a pair to a more recent machine/graphics card?

the renderer would have to be frame-locked with the display (unlike most games that pump out as many frames as they can), not to mention render to a different camera every other frame. you would need some way to accurately synchronize the display frame switching with the glasses. serial/usb might be too slow/have too much latency, so maybe tap into the monitor’s refresh signal?

LCD Shutter-glasses have been around at least since the early nineties. And you’re right about it having to be frame-locked with the display – no amount of coding in software land will get you desirable results.

IIRC, some older commercial cards (Voodoo2 I think) actually came *with* glasses like this, but they never really caught on. They had a dedicated port (1/8 jack) on the card to handle all this.

A superior hack would be to somehow snoop the VGA signals coming from a more recent card (like on the port itself) in order to drive the shutters on just about any hardware imaginable; just use a pic to listen for vsync and bob’s your uncle. Then it’s just a matter of providing a switch to flip which shutter (L or R) is dominant since there would be no way to know which frame (L or R) is being rendered.

@2: Actually it’s correct. “An” is used when the beginning sound of a given word has a vowel sound, such as “entry” or “honor”. In the case of “SGI”, the letter ‘S’ is pronounced “Ess”, so “an” is the correct form of the word.